It doesn't have to be out or round or off center. Having wood a bit proud of the nib or center band even when perfectly round - would you pay $100.00 - $200.00, $300.00 or more for one in which the maker did not make it to a fine tolerances?
I doubt that many pen turners would get complaints from people about a pen being out of round; instead the potential buyers would probably just inspect the pen and walk away without saying a thing. As John said, people remember poorly constructed pens.
As an example, (while I don't sell commercially and only on occasion for a special person or two) when I make pens for family and coworkers, they don't complain, but they are round and finished with a fine finish. However as to close inspection - last spring, I showed a few of my pens to some friends in my small hometown back in the States. Their first impression of a "Jr Emperor" (a $50 KIT) brought up the question "Do you make pens with better gold or fine silver?" Yes, people notice the quality of the turning, assembly, finish and even plating.
The perfect fit and finish were not in question, just the plating was not up to their standards. (One was my HS physics teacher and the other two (high school classmates of mine) are lawyers, and they notice such things. The point is, if they were looking for better quality metallic parts, they certainly would spot defects in the fitting or finish.